Gil,
Not really like a Robinson which used a vertical displacer and horizontal power cylinder (reversed in your model and HOG engines. Robinson also didn't use walking beam linkages. Again, don't mean to be critical--it's a very nice little engine. It seems ANY unique model engine design is going to be copied these days by either China or India.
Hi Brent, You are correct.... most any unique design will be copied and it isn't just the Chinese and Indians.
Here is a German built Stirling Cycle Beam Engine. Herman Bohm started designing and making Stirling Cycle Engines in 1990 which is 7 years before HOG began. I don't know just when he came up with his first beam engine but I think it was early on.
This video from Ministeam
https://youtu.be/DbdbP3M7Opw